Plate holding mechanism for stereotype printing plates



June 23, 1953 J. o. cRABTRl-:E

PLATE HOLDING MEcHANIsM PoR sIEREoIYPE PRINTING PLATES Filed aan. 1o, 195o lNVEN'roR me.. 9m

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Patented June 23, 1953 OFFICE PLATE HOLDING MECHNISM FOR STEREOTYPE PRINTING PLATES John Oldleld Crabtree, London, England, as-

signor to R. Hoe & Co., Inc.,-.New York, N. Y.,

a corporation of New York Application January 10, 1950, Serial No. 137,863

In Great Britain January 10, 1949 Y 4 Claims. (Cl. 101-378) This invention relates to mechanism for use in holding stereotype printing plates to the cylinders of rotary printing machines.

With the increase in operating speeds at which such machines are required to operate, an in- 5 ness of the plate itself. Certain at least of these creasingly important factor affecting the ability plate-holding devices can-be arranged in themof the normal plate-clamping mechanism to hold selves to hold the plate against endvvise and/or the plate in position is the centrifugal force which circumferential movement on, the cylinder alacts on the plate. This forcey which is of course though if desired other devices which play no part radial to the cylinder, tends to cause radial bulgin holding the plate down to the cylinder in the ing of the plate. radial sense could be usedand these .also would The most normal type of clamping mechanism preferably cooperate with the undersurface of the operates against theends of the plate and implate. y e poses on the metal of the plate a compressional The invention is illustrated in the accompanystrain which, the greater it is made to secure the ing draWngS in Which Figure 1 S a lOIlgtudnal plate the more it tends in itself to assist the sectional elevationshowing part of the length'of buckling action arisingl out of the centrifugal a printing Cylinder incorporating this invention, forces involved. and Figure 2 is an end sectional elevation of Fig- In another type of mechanism the plate is subure 1, Figure 3 va detail sectional view and Figure n jeeted at its ends te tension aeung either along 4 a diagrammatic development of a printing plate the length of lthe plate or around thecurve of the for use with this invention. Y y n plate. This mechanism results in subjecting the In'the drawings, the reference l indicates `amet-a1 of the plate te a tensienal strain which (so printingr cylinder and the reference .2' the printfar as concerns the centrifugal force) is in a diing plate. F01 the purpose 0f the invention the rection at right angles to that force and in conplate 2 is formed at its under or concave surface sequence has to be considerable with the result with a series of clamping lugs which can be that the metal tends to tear, for its nature is such formed by undercut recesses or as shown by lunthat it is less adapted to resist tension than comderout projectionsv 3 Which are all Within the pression, boundary edges of the plate and which are dis- The present invention has for its object to protributed over the area of the plate.` The lugs can vide a clamping mechanism in which the defects be longitudinal of the plate but in the particular of the known mechanism are avoided. Aform shown in Figure 4, the lugs are formed'by Broadly stated the present invention consists circumferential ribs extending from the underin providing a printing cylinder with a number surface of the plate,'parallel with and preferably of plate-holding devices which are spaced apart to the same extent as theusual internal ribs 4, as over the plate-receiving area of the cylinder and shown in Figure 1, the ribs 3 acting as do the ribs each of which is so formed as in itself to grip the 4 to strengthen the plate and support it and also plate at its undersurface to hold the plate against acting as clamping projections. These lugs could movement radially outwards of the cylinder. however be local, i. e. correspond only to short 1 The various plate holding devices could take 40 sections of the ribs. f Y different forms in general each would be con- Now, for the purpose of holding a plate to the structed to grip a plate either about an undercut cylinder the cylinder is provided with a series of or dovetail projection extending from the plate projecting plate grippingdevices disposed to enat its undersurface or Within a dovetail undercut gage the lugs 3 formed in undercut areas of the recess in the plate, the former arrangement being plate: In the particular arrangement as indipreferable. cated by Figure 4, sixteen sets of gripping de- It will be clear that with this arrangement the vices are used, these devices being indicated genplate is held clown 'to the cylinder at a number of erally by reference 5. f places all within the boundary of the plate and at These gripping deVCeS 5 are arranged in loneach of which the plate is virtually gripped to 5o gitudinal sets of four and each set comprisesas the cylinder. This result is achieved without relyshown in Figures 1 and 3 two components 6,.1 ing on forces (Whether compressional or ten- Both 'components are formed with undercut prosional) acting along the plate from one end to the jections 8 toembrace the dovetailed klugs 3. One other and in addition the forces which the decomponent 6 has a tubularextension 9 which vices have to exert are in line with the radial houses aspring l0 Which acts between the Comforces to which they have to react.

By arranging a suliicient number of holding devices it is possible tov preclude for all practical purposes any bulging of the plates between its held-down parts by reason of the inherent stiffponent 6 and a flange H on a sleeve I2 on which .at 2I, the slots receivingthe component S is slidable up to a limit stop I2. The other end of this sleeve I2 is screw-threaded at I3 and engages an internally screw-threaded opening in the other component 1. The upper surface of the extension 9 and the corresponding surface of the component 1 are flush with the peripheral surface of the cylinder I.

The various sleeves I2 are disposed (for each longitudinal set of four plate grips) on an operating rod I4 on which the sleeves can slide but not turn, the rod I4 and the bores of thefsleeves being flattened or keyed for that purpose. The components 6 and 1 are flanged at 23 and are slidable in longitudinal grooves I5 by which they are held against rotation so thatv by turning the rod I4 the screw engagement `between the sleeve I2 and the components 6 will causeithecomponents 6 and 1 to be moved towards and awayfrom one another: more particularly the turning of the rod I4 will cause all of the gripping devices E, 1 mounted on it to move their projections 8 into and out of clamping cooperation with the various ribs 3, the pressure exerted being a resilient one by the action of the springs I0 which are compressed by the continued operation of the rod I4 after any pair of components 6 and 1 have engaged and gripped the respective dovetailed projections 3.

For the .purpose of affording a longitudinal location of the plate one of the components 1 is fixed against longitudinal movement. The particular component selected would preferably be v that nearest to one edge of the plate and in the drawings this component is marked with the additional reference X. This location is effected by a locating bar I6 having a lug I1 entering a notch in that component 1X so that this coniponent is fixed longitudinally with the result that when .the rod I4 is turned the mating component 6 will be drawn towards the component 1X and the plate will thus be locked in the longitudinal sense against the component 1X.

To afford tolerance for the variations in the formation of the various ribs 3 on diiierent plates, the other components 1 are also located by the locating bar I6 but with a small float or freedom by making the lug I1 a loose fit in the notch in the corresponding component 1.

In the particular case shown, the plate 2 extends over about 180 larc o the cylinder I and four rods I4 with their associated parts are employed.

While each rod I4 can be separately operated, it is preferred as shown in Figure 2 to arrange the various rods for one plate 2 to be operated together. This is effected by fitting each rod with a gear wheel I8 and inter-gearing the gears I8 by pinions I8 one of which can have a head 20 to receive an operating wrench.

As is indicated in Figure l, the rods I4 can be extended to operate similar gripping components 6, 1 for a second plate the end of which is shown at 2. Moreover, in the drawing only one diametral half of a cylinder is shown. The other half of the cylinder would of course be'equipped similarly to the half shown.

In order to enable the sets of gripping components 6, 1 to be adjusted for printing plates of different sizes and also for obtaining register in multi-colour work, the location bars I6 can be adjusted longitudinally, the sets of vcomponents S, 1 (which are free to slide along the rods I4) being caused to partake of the adjustment: such adjustment can be provided by 'slotting the bars I6 locking 'screws 22. A

- tions arranged in groups, a

fine adjustment mechanism (not shown) could be provided to adjust the bar.

I claim:

1. In combination a printing cylinder, a curved stereotype printing plate having distributed over its concave surface a series oi undercut projections, arranged in groups, a corresponding series of gripping devices arranged in corresponding groups, each gripping device comprising a rst component constituting an abutment and a second component to clamp a projection between them, means to locate the first component of a gripping device of each group to be engaged by a projection, and to allow limited free movement of the first component of each other device of the group, means to operate the second components of each group to move them relatively into and out of embracing engagement with their respective projections, the said operating lie-ans operating on the second component of each device through a resilient component.

2. In combination a printing cylinder, a curved stereotype printing plate having distributed over its concave surface a series of transverse undercut projections arranged in groups extending longitudinally or Athe plate, a corresponding series of gripping devices mounted on the cylinder and arranged in corresponding longitudinal groups, each device comprising two gripping components, a first component constituting an abutment and a second component to clamp a projection between them, means to locate longitudinally a first component of one device of each group and to locate with limited freedom the first gripping components of the other devices of the group, an operating component for the devices of each group adapted to move the second components into embracing engagement with their respective projections, and spring means associating the second gripping components o each group to its operating component.

3. In combination a printing cylinder, a curved stereotype printing plate having distributed over its concave surface a series of undercut projeccorresponding series of gripping devices arranged in corresponding groups, each gripping device comprising two components to embrace a projection between them, means to operate the components of each group simultaneously to move into and out o embracing engagement with the projections, means to locate one component of a gripping device of each group and to allow limited free movement of one component of each other device of the group, means to adjust the locating means, means to operate the components of each group to move them relatively into and out of embracing engagement with their respective projections, the said operating means operating on the second component of each device through a resilient component.

4. In combination a printing cylinder, a curved stereotype printing plate having distributed over its concave surface a series of transverse undercut projections arranged in groups extending longitudinally of the plate, a corresponding series of gripping devices mounted on the cylinder and arranged in corresponding longitudinal groups, each device comprising two gripping components, means to locate longitudinally one component of one device of each group, and to locate with limited freedom the corresponding gripping components of the other devices of the group, means to adjust the locating means, an operating component for the devices of each group, the said component operating to move the two components into embracing engagement with their respective projection, and spring means associating the second gripping components of each group to its operating component.

JOHN OLDFIELD CRABTREE.

References Cited in the file of this patent UNITED STATES PATENTS Number Number 6 Name Date Wheat Nov. 14, 1911 Schmidt May 29, 1923 Halliwell Nov. 22, 1927 Crafts July 24, 1928 Tomlin Dec. 25, 1934 Horton Dec, 25, 1934 'Wood Mar. 31, 1936 

